The role of propagule availability in determining community composition is poorly understood, and is infrequently investigated for bryophytes. In addition the extent to which spore availability is limited by dispersal is unknown. If spore availability is not dispersal-limited, local and regional spore dispersal and wind availability may affect spore availability at any point. In this study, the abundance of Sphagnum spores was investigated
within the context of a successional sequence where Sphagnum spp. invade a feather moss community in black spruce boreal forests of northwestern Que´bec, Canada. Spores were trapped and grown in a greenhouse to protonemal stage to estimate the abundance of spores within three sites that varied in Sphagnum abundance, and stand density (a surrogate for wind intensity). Sporophyte production was also investigated in one site where individual Sphagnum colonies could be distinguished. Spores were less abundant in sites with less ground cover of Sphagnum present in the community, although spores were trapped in all sites. Spore abundance was inversely correlated with local stand density, indicating that wind intensity may play a role in limiting dispersal. Sporophytes were produced in colonies that were larger and had greater access to light. These results suggest that Sphagnum invasion into young dense forests may be partially limited by spore dispersal, although the availability of germination substrates may also play an important role.

Sphagnum, spore abundance, sporophyte abundance, boreal forest, dispersal, Quebec, Canada